A plasma display capable of realizing a large screen, a reduced thickness and a light weight becomes widely available as a display device for use in a computer monitor, a television receiver, and the like.
As a plasma display panel (hereinafter, referred to as a PDP) of the plasma display, it has been known that there are PDPs of two types, that is, a DC (Direct Current) type and an AC (Alternating Current) type. In particular, the AC type PDP is used typically because it is superior to the DC type PDP in terms of various aspects such as reliability and image quality. Hereinafter, description will be given of a configuration of the conventional AC type PDP.
The conventional PDP has a structure that a discharge space is formed between a front panel and a back panel.
The front panel includes a front substrate, and a plurality of display electrode pairs formed in stripes on one side of the front substrate. The display electrode pair is provided with a strip-shaped scanning electrode and a strip-shaped sustaining electrode arranged in parallel with each other. A strip-shaped shielding layer (a black stripe) is formed between the adjacent display electrode pairs. A dielectric layer is formed on the display electrode pair and the shielding layer to cover the relevant side of the front substrate. A dielectric-protective layer is formed to cover the dielectric layer.
The back panel includes a back glass substrate, a plurality of address electrodes formed in stripes on one side of the back glass substrate, and a dielectric glass layer formed to cover the address electrodes. A plurality of partition walls are formed in stripes on the dielectric glass layer. These partition walls are arranged in parallel with the address electrodes such that each address electrode is located between the adjacent partition walls when being seen in a thickness direction of the back panel. Moreover, the dielectric glass layer and side surfaces of the adjacent partition walls form a groove coated with a red phosphor layer, a green phosphor layer, or a blue phosphor layer.
In the PDP, the front panel and the back panel, which are configured as described above, are disposed such that the respective electrode formation sides are opposed to each other. Further, peripheries of a space between the front and back panels are sealed with a seal member such as frit glass, so that the PDP has a hermetically-closed structure. In this hermetically-closed structure, a hermetically-closed space is formed and is filled with a discharge gas containing neon (Ne), xenon (Xe), and the like at a pressure of 400 Torr to 600 Torr, so that a discharge space is formed. In the PDP, a video signal voltage is selectively applied between the display electrode pair and the address electrode, so that gas discharge occurs at the discharge space. More specifically, address discharge for charge accumulation on a surface of the dielectric-protective layer occurs between the scanning electrode and the address electrode in the discharge space intended to emit light. On the other hand, sustain discharge for generation of ultraviolet rays for use in image formation occurs between the scanning electrode and the sustaining electrode in the discharge space where the electric charge is accumulated. In the PDP, the ultraviolet rays are generated by the gas discharge, and each phosphor layer is excited by the ultraviolet rays to emit visible light. Thus, the PDP can display a color picture.
With regard to the PDP, recently, demand for higher definition grows, and a full HD (High Definition) (1920×1080 pixels: progressive display) PDP capable of realizing low cost, low power consumption, and high brightness is required in the market.
In order to satisfy the requirement, there has been known a method for improving an initial electron emission characteristic (hereinafter, referred to as an electron emission characteristic) of the dielectric-protective layer for causing the address discharge. In order to improve the electron emission characteristic of the dielectric-protective layer, for example, Si (silicon) or Al (aluminum) is added to the dielectric-protective layer made of MgO (magnesium oxide). This method allows increase of a frequency of emitting initial electrons from the dielectric-protective layers, leading to prevention of erroneous address discharge (so-called write defect) that results in flicker of an image.
In the case of improving the electron emission characteristic of the dielectric-protective layer, however, there arises an issue of increase of an attenuation factor that indicates reduction, with time, of a charge accumulation amount as a memory function of the dielectric-protective layer, because of the increase of the frequency of emitting initial electrons from the dielectric-protective layer. The reduction of the charge accumulation amount causes a low potential difference between the scanning electrode and the address electrode, resulting in increase of a voltage required to start the address discharge (hereinafter, referred to as a discharge start voltage). In other words, a trade-off relation is established between the improvement in electron emission characteristic of the dielectric-protective layer and the suppression of increase of the discharge start voltage.
In order to improve this issue, for example, Patent Document 1 (WO 2004/049375 A1) and Patent Document 2 (JP 2008-16214 A) disclose a technique of dispersing and arranging fine particles containing a crystal of a metal oxide on the surface of the dielectric-protective layer.
According to this technique, the dispersed and arranged fine particles improves the electron emission characteristic; therefore, the dielectric-protective layer does not need to improve the electron emission characteristic and is sufficient to only have a function of accumulating the electric charge to suppress the increase of the discharge start voltage. In other words, this technique can improve the issue in such a manner that the dispersed and arranged fine particles and the dielectric-protective layer share a role in improving the electron emission characteristic of the dielectric-protective layer and a role in suppressing the increase of the discharge start voltage.